(AFP) – British police have announced it is investigating the death of a Russian businessman with links to a former Kremlin critic amid increasing tensions between London and Moscow over a nerve agent attack on a double spy in Britain earlier this month.

Police said in a statement on Tuesday that counter-terrorism detectives were leading the investigation into the death of a man in his 60s who lived on Clarence Avenue in suburban south-west London.

The statement would not elaborate on the name of the man, but reports said he was Nikolai Glushkov, a Russian associate of late tycoon Boris Berezovsky. Glushkov, 68, was found dead late on Monday. His death comes more than a week after Sergei Skripal, a former Russian spy, was found unconscious with his daughter on a bench outside a shopping center in the southern town of Salisbury.

The poisoning attack has been likened to a death in 2006 of a Russian spy in Britain who was supposedly killed by Russian agents. The British government has demanded an explanation from Russia over a suspected chemical attack, saying the nerve agent used to poison Skripal was from the Soviet era.

The Metropolitan Police said the Glushkov’s death was not linked to Skripal’s case.

“There is no evidence to suggest a link to the incident in Salisbury,” it said in a statement, adding, however, that the counter-terrorism police was deployed “because of associations that the man is believed to have had.”

Glushkov had worked in various capacities for Berezovsky, one of Russia’s most powerful figures in the years after the collapse of the Soviet Union, who fled to London in 2000 after a row with Russian authorities. Berezovsky committed suicide in March 2013, 10 years after he was granted political asylum in Britain.